Splash has no area of effect or effect on the user, and thus does nothing but show its animation. However, the user can choose which direction to perform it in; this has no effect on the move itself, but the user will be left facing the same direction (and thus is not necessarily equivalent to waiting the turn, which would give the user no opportunity to change their facing). Unlike most moves in Pokémon Conquest, Splash can be used even if it would have no target (presumably because it never has a target).

Trivia

Splash is the only move that has been introduced that does nothing to either the opponent or the user. In Pokémon Mystery Dungeon, however, a Pokémon using Splash will deal 5 damage to itself and its opponent if it comes in contact with any other Pokémon.

Every Pokémon that can learn Splash by leveling up learns it as a starting move.

While the English name suggests an association with water, the Japanese name, はねる (haneru), can mean both "splash" and "hop" (although usually the latter). This explains why the move can be learned naturally by Pokémon such as Spoink and Hoppip — species who have no association with water but are known for hopping or jumping and why Gravity disables it. The translation as "Splash" was likely due to the fact that it was only available to Magikarp when it was introduced.